40918-98-7Relevant academic research and scientific papers
Stereoselective synthesis of cyclobutanes by contraction of pyrrolidines
Hui, Chunngai,Brieger, Lukas,Strohmann, Carsten,Antonchick, Andrey P.
, p. 18864 - 18870 (2021/11/23)
Here we report a contractive synthesis of multisubstituted cyclobutanes containing multiple stereocenters from readily accessible pyrrolidines using iodonitrene chemistry. Mediated by a nitrogen extrusion process, the stereospecific synthesis of cyclobutanes involves a radical pathway. Unprecedented unsymmetrical spirocyclobutanes were prepared successfully, and a concise, formal synthesis of the cytotoxic natural product piperarborenine B is reported.
Non-Chelate-Assisted Palladium-Catalyzed Aerobic Oxidative Heck Reaction of Fluorobenzenes and Other Arenes: When Does the C?H Activation Need Help?
Albéniz, Ana C.,Villalba, Francisco
supporting information, p. 4795 - 4804 (2021/09/06)
The pyridone fragment in the ligand [2, 2’-bipyridin]-6(1H)-one (bipy-6-OH) enables the oxidative Heck reaction of simple arenes with oxygen as the sole oxidant and no redox mediator. Arenes with either electron-donating or electron-withdrawing groups can be functionalized in this way. Experimental data on the reaction with toluene as the model arene shows that the C?H activation step is turnover limiting and that the ligand structure is crucial to facilitate the reaction, which supports the involvement of the pyridone fragment in the C?H activation step. In the case of fluoroarenes, the alkenylation of mono and 1,2-difluoro benzenes requires the presence of bipy-6-OH. In contrast, this ligand is detrimental for the alkenylation of 1,3-difluoro, tri, tetra and pentafluoro benzenes which can be carried out using just [Pd(OAc)2]. This correlates with the acidity of the fluoroarenes, the most acidic undergoing easier C?H activation so other steps of the reaction such as the coordination-insertion of the olefin become kinetically important for polyfluorinated arenes. The use of just a catalytic amount of sodium molybdate as a base proved to be optimal in all these reactions. (Figure presented.).
Palladium-catalyzed C-C bond formation of arylhydrazines with olefins via carbon-nitrogen bond cleavage
Zhu, Ming-Kui,Zhao, Jun-Feng,Loh, Teck-Peng
supporting information; experimental part, p. 6308 - 6311 (2012/01/06)
The unactivated carbon-nitrogen bond of various aryl hydrazines was cleaved under very mild conditions by Pd(0) with the assistance of Pd(II). The in situ generated aryl palladium complex readily takes part in the C-C bond formation with olefins. This study offered a new mode of C-Pd bond formation, which will spur the development of palladium-catalyzed cross-coupling in the future.
Enantioselective sequential conjugate addition-allylation reactions: A concise total synthesis of (+)-podophyllotoxin
Wu, Yingming,Zhao, Jingfeng,Chen, Jingbo,Pan, Chengxue,Li, Ang,Zhang, Hongbin
supporting information; experimental part, p. 597 - 600 (2009/09/25)
(Chemical Equation Presented) A highly flexible and concise total synthesis of (+)-podophyllotoxin featured with an enantioselective sequential conjugate addition-allylation reaction was reported. Starting from commercially available 3,4,5-trimethoxycinna
Parallel synthesis of homochiral β-amino acids
Davies, Stephen G.,Mulvaney, Andrew W.,Russell, Angela J.,Smith, Andrew D.
, p. 1554 - 1566 (2008/02/09)
The parallel asymmetric synthesis of an array of 30 β-amino acids of high enantiomeric purity using the conjugate addition of homochiral lithium N-benzyl-N-(α-methylbenzyl)amide as the key step is accomplished. The experimental simplicity and highly practical nature of the protocol is demonstrated by the efficient parallel conversion of 15 α,β-unsaturated esters to both enantiomeric series of the corresponding β-amino acids in high overall yields and selectivities with minimal purification involved in each step of the reaction protocol.
Imidazolylidene carbene ligated palladium catalysis of the Heck reaction in the presence of air.
Liu, Jingping,Zhao, Yuanhong,Zhou, Yongyun,Li, Liang,Zhang, Tony Y,Zhang, Hongbin
, p. 3227 - 3231 (2007/10/03)
Five 1,3-disubstituted imidazolium salts were synthesized. Their Heck reaction activities were evaluated. A convenient, efficient and high yielding procedure based on these compounds for the arylation of olefins was developed. Heck reactions mediated by these palladium-N-heterocyclic carbene complexes were conducted under air and even in the presence of several common oxidants.
Mild and efficient aryl-alkenyl coupling via Pd(II) catalysis in the presence of oxygen or Cu(II) oxidants
Parrish, Jay P.,Jung, Young Chun,Shin, Seung Il,Jung, Kyung Woon
, p. 7127 - 7130 (2007/10/03)
We report herein a mild and efficient method for carbon-carbon bond formation between aryl stannanes and olefins via Pd(II) catalysis in the presence of oxygen or Cu(II) oxidants as a reoxidant. The process allows reactions between various olefins and aryl stannanes of varying electron density. Coupling methods under these oxidation conditions are comparatively described, and the benefits and limitations are also discussed.
Aromatic β-amino acids as Asp-Phg mimics in LDV derived VLA-4 antagonists
Wehner, Volkmar,Blum, Horst,Kurz, Michael,Stilz, Hans Ulrich
, p. 2023 - 2036 (2007/10/03)
Aromatic β-amino acid esters 2a-h were prepared in racemic and enantiomerically pure form by the Radionow reaction or based on the method described by Davis and used as mimics of the Asp-Phg C-terminus in LDV derived VLA-4 antagonists. As a promising β-am
Use of (S)-N-tert-butoxycarbonylaziridine-2-carboxylate derivatives for α-amino acid synthesis
Baldwin, Jack E.,Farthing, Christopher N.,Russell, Andrew T.,Schofield, Christopher J.,Spivey, Alan C.
, p. 3761 - 3764 (2007/10/03)
(S)-tert-Butyl-N-tert-butoxycarbonylaziridine-2-carboxylate and (S)-tert-butyl-N-tert-butoxycarbonylaziridine-2-carboxamide were synthesised and found to react with copper 'catalysed' Grignard reagents to give protected α-amino acids in moderate to good yields.
